It has been known that a sensitivity parameter of a smoke detector can be periodically altered in response to day/night cycles. The known sequence increases the sensitivity at night and decreases it during the day. Such changes can be effected automatically in response to incident light.
At times there is continued light in a region even at night. Hence, it would be desirable to be able to respond to more than the level of ambient light in changing sensitivity. Additionally, if the light being sensed is from a developing fire condition, it would be desirable to take that information into account in making a fire determination. It would also be advantageous if information obtained from the light sensor could be used to speed up the fire detection process and/or minimize nuisance alarms.